In the past, an optical coherent tomography diagnosis apparatus (OCT: Optical Coherent Tomography) has been used as an image diagnostic apparatus for arteriosclerosis diagnosis to diagnose before surgery under an endovascular treatment by a high performance catheter such as a balloon catheter, a stent and the like or for confirming the results of such treatment.
An optical coherent tomography diagnosis apparatus is an apparatus in which, in a state in which a catheter with a built-in optical lens and an optical fiber mounted with an optical mirror at the distal tip thereof is inserted into a blood vessel, measuring light is light-emitted in the blood vessel while rotating the optical mirror, and radial scanning is carried out by receiving reflected light from biological tissue. A tomographic image of the blood vessel is created based on the coherent light by making interference between the obtained reflection light and reference light divided from the measuring light beforehand.
Further, an optical coherent tomography diagnosis apparatus has recently been diagnosed which utilizes wavelength-sweeping for an improvement type of optical coherent tomography diagnosis apparatus.
The basic structure of the wavelength-sweeping optical coherent tomography diagnosis apparatus is similar to that of the optical coherent tomography diagnosis apparatus (OCT), but one aspect involves the use of a light source having a longer wavelength than that of the optical coherent tomography diagnosis apparatus and also lights having different wavelengths are light-emitted continuously. The mechanism for varying the light path length of the reference light is made unnecessary by obtaining reflection light intensity at each point in the depth direction of the biological tissue by using frequency analysis of the coherent light.
Any of the optical coherent tomography diagnosis apparatus mentioned above has a characteristic that the stronger the intensity of the emitted measuring light, the more clear the extracted tomographic image becomes. It is thus desirable, on the occasion of measurement, to use the apparatus by raising the intensity of the measuring light as much as possible in a range not injuring the biological tissue.
However, problems arise when the apparatus is used by raising the intensity of the measuring light. Generally, the light source of the optical coherent tomography diagnosis apparatus requires a certain amount of time for the start-up. Therefore, upon diagnosis a catheter is inserted into a blood vessel usually in a state in which the light source is activated beforehand. In other words, when inserting the catheter into the blood vessel, it is in a state in which the measuring light is already being emitted from the distal portion thereof and so it happens on the occasion of diagnosis that the measuring light is illuminated continuously at the periphery of the apparatus.
Here, the measuring light used in the optical coherent tomography diagnosis apparatus is generally a near-infrared ray and is invisible to human eyes, so if an individual (i.e., the eyes of an individual) is subjected to the illumination, it cannot be expected that the individual will react to avoid the illumination. For this reason, it is considered that some sort of influence (undesirable influence) will occur before and after the diagnosis, for example in a case in which the measuring light is illuminated by chance continuously on the eyes of persons in the surrounding area.
Also, with respect to a test subject, the measuring light will illuminate the same position of a biological tissue continuously during the diagnosis in a case in which the rotation of the optical mirror stops in a state in which the catheter is inserted into a blood vessel or the like.
In such a case, even if the intensity of the emitted measuring light is suppressed within a range not damaging to the biological tissue, some amount of influence is exerted on the biological tissue as a result of being illuminated continuously.
A proposal has been made, for example in a Patent Document 1 (Japanese unexamined Publication No. 2006-15134), in which a state of attachment and detachment for a probe is detected and in a case in which it is judged that the probe is not connected, the drive of the light source is stopped.
However, the light source of the optical coherent tomography diagnosis apparatus requires a long time period from a stop state to a state in which it becomes possible to supply a stable light. If the light source is activated after detecting the state of attachment and detachment for the probe, a lot of time may be required until it reaches a usable state.